Optical-Thermal Response and Dynamic Thermal Damage of Bio-Tissue During Laser Thermotherapy

2003 ◽  
Author(s):  
G. M. Zhu ◽  
W. Liu ◽  
T. F. Zeng ◽  
K. Yang
Keyword(s):  
Thermal Injury ◽  
Thermal Damage ◽  
Tumor Tissue ◽  
Local Heating ◽  
Damage Model ◽  
Thermal Response ◽  
Tumor Treatment ◽  
Thermal Coagulation ◽  
Laser Head ◽  
Temperature Damage

Laser thermotherapy is a technique used for tumor treatment. It generates a local heating, causes thermal coagulation of living tissue and eliminates the tumor. Precise heating of tumor tissue with healthy minimum thermal injury to adjacent tissue is essential to thermotherapy. Understanding of heat transfer and optical-thermal interaction is important for control of temperature and design of thermotherapy. This study applies the Arrhenius damage model to describe the heat-induced change of optical properties. It calculates the distribution temperature, damage and optical-thermal response of bio-tissue during the laser treatment, and shows how these factors affect the effectiveness of laser thermotherapy. Similar research has been performed by Kim and coworkers [1996], Iizuka and coworkers [2000], and Whelan and coworkers [2000]. This study relaxes some conditions in previous investigations. It reveals the importance and the effect of size of the laser head.

Assessment of Possible Thermal Damage of Tissue due to Atherectomy by Means of a Mechanical Debulking Device

2008 ◽  
Author(s):  
Ryang D. Lovik ◽  
John P. Abraham ◽  
Eph M. Sparrow
Keyword(s):  
Numerical Simulations ◽  
Thermal Injury ◽  
Thermal Damage ◽  
Threshold Value ◽  
Posterior Tibial Artery ◽  
Artery Wall ◽  
Flow Rates ◽  
Injury Index ◽  
Orbital Atherectomy

In vitro and cadaver experiments, coupled with numerical simulations, were performed to assess the possibility that orbital atherectomy might cause thermal damage of tissue. The experiments involved debulking operations on a surrogate artery and on the plaque-lined posterior tibial artery of a cadaver. Temperatures and coolant flow rates measured during these experiments enabled a numerical simulation of the debulking of a plaque-lined artery in a living human. The temperature variations from the numerical simulations were used to evaluate a thermal injury index. The resulting values of the index were found to be several orders of magnitude below the threshold value for thermal injury. It is concluded that it is extremely unlikely that the use of an orbital debulking device, the Diamondback 360°™ (Cardiovascular Systems, Inc.), can lead to thermal injury of the artery wall.

scholarly journals PECULIARITIES OF THE WOUND PROCESS DEVELOPMENT IN PATIENTS WITH THERMAL INJURY WHEN USED SILVER PREPARATIONS IN BURN WOUNDS SURGICAL TREATMENT

2021 ◽  
pp. 81-87
Author(s):  
N. V. Tuzyuk
Keyword(s):  
Metabolic Activity ◽  
Functional Activity ◽  
Thermal Injury ◽  
Thermal Damage ◽  
Main Group ◽  
The Body ◽  
Metabolic Reaction ◽  
Neutrophilic Granulocytes ◽  
Burn Wound ◽  
Significant Activation

Fundamental research in the field of burn wound development process highlights new pathogenetic mechanisms that underlie the improvement of medical practice, the main purpose of which is to create optimal conditions for early regeneration of the affected skin, as well as to eliminate the development of local and general complications. Irrational general and local treatment of wounds contribute to the slowing down of regenerative processes, thereby worsening the prognosis and consequences of thermal injury. It was found out that in patients of both study groups in the first period of the study the characteristics of the cellular composition of the wound impressions of the wound bottom of the area of thermal damage correspond to the degenerative type. In patients of the main group in the second term of the study in the area of thermal damage cells with high levels of functional and metabolic activity begin to appear, which increase antimicrobial resistance and reduce the risk of generalization of the infectious process which is the main source of burns. In patients of the main group, an increase in the activity of neutrophilic granulocytes in the induced test was found in the second term of the study, which, in our opinion, indicates the involvement of neutrophilic granulocytes with high functional and metabolic activity. Under conditions of significant activation of resident monocytes in response to injury in patients of the main group in the second and third term, the area of thermal damage migrates functionally effective monocytes. In patients of the main group the preservation of the activity of myeloperoxidase - the main enzyme of the oxygen-dependent phase of phagocytosis at the minimum subcompensated level, which leads to the preservation of the oxygen-dependent metabolic reaction of neutrophilic granulocytes in the subsequent study, Increases in the content of PAS-positive substances in neutrophilic granulocytes indicate the preservation of the functional reserve for activation and completion of the oxygen-independent phase of phagocytosis. The use of the developed treatment promotes the involvement of functionally active phagocytic cells in the burn wound, reduces the toxic load on monocytes and neutrophils, which helps to maintain their functional activity at the subcompensated level. These trends in patients of the main group reduce the risk of both local and general infectious complications of burn disease. It was found that the level of spontaneous functional activity in the HCT test is associated with the activity of resident monocytes. They form the primary barrier that protects the body from infection or harmful macromolecular complexes. Monocytes - "inflammatory", which constantly come from the free pool and their functional activity against microbial antigens is much higher than resident monocytes. An indicator of the activity of monocytes - "inflammatory" is an indicator of functional activity in the induced HCT test. The results of the study indicate that under conditions of significant activation of resident monocytes in response to injury in patients of the main group in the second and third terms of the area of thermal damage migrate functionally effective monocytes.

An elevated temperature damage model for 45Cr4NiMoV steel heavy backup rollers

2019 ◽  
Vol 6 (8) ◽  
pp. 086553 ◽  
Author(s):  
Chen Xuewen ◽  
Wang Nana ◽  
Du Yuqing ◽  
Wang Guangxin ◽  
Zhang Jingli ◽  
...  
Keyword(s):  
Elevated Temperature ◽  
Damage Model ◽  
Temperature Damage

Ultrasound Hyperthermia: Dose Estimation and Device Design

2012 ◽  
Author(s):  
Danica Gordon ◽  
Chandrasekhar Thamire
Keyword(s):  
Cancer Treatment ◽  
Treatment Modality ◽  
Thermal Damage ◽  
Operating Parameter ◽  
Cell Types ◽  
Temperature History ◽  
Device Design ◽  
High Frequency Ultrasound ◽  
Treatment Protocols ◽  
Thermal Coagulation

As a cancer treatment modality, thermal ablation offers the advantages of being less invasive and posing fewer post-procedural complications compared to traditional cancer therapies. It involves destroying cancerous cells by subjecting them to the appropriate amount of heat dose. In the present study, high frequency ultrasound (US) ablation is theoretically examined for effectiveness as a treatment modality for intraluminal and extracorporeal cancer treatment. Objectives of this study are to 1) develop thermal-damage correlations for a variety of cancer cells and 2) design US treatment devices, based on thermal damage correlations developed, and treatment planning protocols. To achieve these goals, thermal damage information for different cell types is first determined from earlier studies or pilot experiments. Required US doses for specific tissues are determined next through numerical experiments. Device design and estimation of thermal coagulation contours is then performed by comparing temperature-history data against the thermal-damage data for a range of device parameters. Treatment protocols are finally developed based on the analysis of the results for a range of applicable device parameters. Results are presented in terms of correlations for the volume and location of ablated tissue corresponding to a range of operating parameter values.

Ultrasound Hyperthermia: Dose Estimation and Device Design for Intraluminal and External Delivery

2012 ◽  
Author(s):  
Danica Gordon ◽  
Chandrasekhar Thamire
Keyword(s):  
Thermal Damage ◽  
Treatment Time ◽  
The Body ◽  
Thermal Therapy ◽  
Surrounding Tissue ◽  
Temperature History ◽  
Published Data ◽  
Device Design ◽  
Treatment Protocols ◽  
Thermal Coagulation

Thermal ablation in the context of this study refers to destroying cancer cells by heating them to supraphysiological temperatures for appropriate times. Once the tumor cells and a small layer of surrounding tissue cells are killed, they are absorbed by the body over time. Compared to open surgery, radiation, and chemotherapy, thermal therapy can be less expensive and pose less risk of harmful post-procedural complications, while possessing the potential to be effective [1]. Currently microwave and radiofrequency ablation are in use for local hyperthermia; however, they lack the ability to focus heat into the target zones effectively or treat larger tumors without affecting the surrounding healthy tissue. In the current study, high frequency ultrasound (US) ablation is examined as a treatment modality because of its ability to focus and control heat effectively. Objectives of this study are to 1) develop thermal-damage correlations for US thermal therapy and 2) design delivery devices and associated treatment planning protocols. To achieve these goals, thermal damage information is first evaluated for a variety of cells and tissues from published data or pilot experiments. Required US dose levels are determined next through numerical experiments, followed by device design and estimation of thermal coagulation contours by comparing the temperature-history data against the thermal-damage data. Based on the analysis of the results for a range of parameters, namely, the applicator power, geometry, frequency, coolant parameters, treatment time, and tissue perfusion, treatment protocols are developed. Intraluminal, external, and interstitial modes of delivery are considered for focal sites in a variety of target areas. In the following sections, methods followed and sample results obtained are presented.

SU-GG-J-152: Predictive Capabilities of Thermal Damage Model for Real Time MR Monitored Interstitial Laser Treatment in a Canine Brain Model

2008 ◽  
Vol 35 (6Part7) ◽  
pp. 2714-2714
Author(s):  
A Shetty ◽  
J Weinberg ◽  
R McNichols ◽  
A Gowda ◽  
S Klumpp ◽  
...  
Keyword(s):  
Real Time ◽  
Laser Treatment ◽  
Thermal Damage ◽  
Damage Model ◽  
Canine Brain ◽  
Interstitial Laser

Experimental Research on the Thermal Damage of Concrete

2013 ◽  
Vol 351-352 ◽  
pp. 460-466
Author(s):  
Chao Chen ◽  
Ying She Luo ◽  
Song Hua Tang ◽  
Xuan Zhang
Keyword(s):  
Damage Evolution ◽  
Thermal Damage ◽  
Damage Model ◽  
Effect Of Temperature ◽  
Compression Tests ◽  
Thermal Compression ◽  
Relevant Reference ◽  
Different Temperatures ◽  
The Relationship ◽  
Fire Design

In order to investigate the effect of temperature (from normal temperature to 850°C) coursed by fire on the strength damage of concrete, thermal compression tests for concrete specimens named C35 have been performed under different temperature conditions. Emphasis is laid on the relationship between temperature and thermal damage strength; and the relevant formula is proposed in this paper. The regularity and mechanism of thermal damage evolution in concrete on strength under high temperature are analyzed. Combined the result of tests with the residual strength thermal damage model, we obtain the specific damage variable value D under different temperatures. Finally, we compare the fitting formula curve to relevant reference; there are some important conclusions which can be partly applied to fire design of concrete structure.

A Theoretical Comparison of the Efficacy of Microwave and Ultrasound Applicators Used in Transurethral Thermal Therapy

2005 ◽  
Author(s):  
Chandrasekhar Thamire ◽  
Rao L. Divi ◽  
Mukesh Verma
Keyword(s):  
Thermal Damage ◽  
Thermal Therapy ◽  
Accurate Estimation ◽  
Transient Temperature ◽  
Thermal Lesion ◽  
Thermal Coagulation ◽  
External Cooling ◽  
Alternating Direction ◽  
Damage Data ◽  
Prostate Tumor Cells

Microwave and ultrasound energy sources are commonly used in minimally invasive thermal therapy for benign prostatic hyperplasia. Successful management of the therapy using either of these methods requires an accurate estimation of the thermal dosage. The purpose of this study is to evaluate, theoretically, the thermal damage caused by typical transurethral microwave and ultrasound applicators for different thermal doses and compare the efficacy of the two methods. Using an Alternating-direction implicit method, the Pennes bio-heat transfer equation is solved for different levels of power and heating times. Internal and external cooling is applied to preserve the urethral and rectal lining and to control the temperatures within the tissue. The extent of thermal coagulation is determined from the resulting temperature histories, using the existing experimental thermal damage data for prostate tumor cells. The temperatures and damage contours calculated are validated using an Arrhenius analysis of the temperature and thermal-lesion data from the available experimental results. Results show that the calculated damage zones are in good agreement with those observed in the experiments. Results from calculations for different combinations of the parameters are presented in terms of the transient temperature histories and radial and axial extent of the lesion shapes. These results suggest that both methods can yield comparable thermal damage, though ultrasound appears to possess an improved control of directional heating.

Thermal Effect of Gold Nanorods in Implanted Prostatic Tumors During Laser Photothermal Therapy

2012 ◽  
Author(s):  
N. Manuchehrabadi ◽  
L. Zhu ◽  
A. Attaluri ◽  
H. Cai ◽  
R. Edziah ◽  
...  
Keyword(s):  
Gold Nanorods ◽  
Photothermal Therapy ◽  
Systematic Approach ◽  
Thermal Damage ◽  
Tumor Tissue ◽  
Laser Energy ◽  
Laser Wavelength ◽  
Temperature Elevation ◽  
Treatment Protocols ◽  
Energy Absorbers

In recent years, nanotechnologies have emerged as promising therapies due to their ability to deliver adequate thermal dosage to irregular and/or deep-seated tumors. Gold nanorods can be tuned to a specific laser wavelength and serve as strong laser energy absorbers. Due to the powerful optical absorption, the laser energy is concentrated in an area congregating by nanorods, and then the energy absorbed can be transferred to the surrounding tumor tissue by heat conduction.1–4 Currently, there are wide variation ranges of treatment protocols using photothermal therapy. A systematic approach is lacking to analyze temperature elevation history in tumors during heating to design an optimized combination of laser parameters to maximize thermal damage to tumors.

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